1. Field of the Invention
The present invention relates to a musical tone control device which controls a musical tone in terms of a specific musical parameter in accordance with a result of the detection for a touch response of the key provided in the electronic keyboard instrument.
2. Prior Art
Conventionally, there is provided a musical tone control device, for an electronic musical instrument, which is disclosed by Japanese Utility-Model Publication No. 55-43438 or the like. This kind of device mainly comprises a shutter mechanism, a pair of detectors and a common light source. Herein, the shutter mechanism contains a pair of shutter plates which operate by being interlocked with swing motions of a keyboard frame in up/down directions as well as in left/right directions, wherein the keyboard frame is provided to support a plenty of keys of the keyboard such that the key can freely move up and down. The common light source radiates light to a pair of detectors while the amount of light radiated is adjusted by a pair of shutter plates respectively. In response to the amount of light received, the detectors generate electric signals which respond to displacement in the swing motion of the keyboard frame. Those electric signals are used as musical tone control signals, by which a certain musical effect realized by the electronic musical instrument is controlled.
The musical tone control device conventionally known has a structure in which the keyboard frame, supported by plate springs, should be swung as a whole. Hence, when the keyboard frame is swung, there is established a movable mechanism whose mass should be equivalent to the total mass of the keys and key-support members. Due to such relatively large mass of the movable mechanism to be established, the conventional device suffers from a bad response. In other words, the conventional device cannot perform the musical-tone control in response to a delicate movement of the key. Or, it is difficult to control the vibrato, whose resonance frequency is low and which gives rapid and minute fluctuations to the pitch.
The conventional device detects the after touch which emerges after the depression of the key. However, it is not possible to detect an initial motion of the key. When the keyboard frame is swung left and right, the conventional device cannot clearly discriminate which direction the keyboard frame is actually swung.